Apparatus for discharging solid material



Oct. 13, 1953 H. v. TRASK ETAL APPARATUS FOR DISCHARGING SOLID MATERIAL 5 Sheets-Sheet 1 Filed Dec. 19. 1951 INVENTORS l/aro/d l/ Wash 2 BY I A ennct zM-fia/ey rafter/7676 Oct. 13, 1953 v, TRAsK ETAL 2,655,365

APPARATUS FOR DISCHARGING SOLID MATERIAL Filed Dec. 19. 1951 3 Sheets-Sheet 2 aide/ways Oct. 13, 1953 H. v. TRASK ETAL APPARATUS FOR DISCHARGING SOLID MATERIAL 3 Sheets-Sheet 3 Filed Dec.

INVENTORS K fla M a Z 06 W0 y m Y Vin WQL

w R N N Patented Oct. 13, 1953 APPARATUS FOR DISCKARGING 8O MATERIAL Harold V. Trash and Kenneth M. Haley, Ashland,

Ky., assignors to Oglebay, Norton and Company, Cleveland, ware Ohio, a corporation of Dela- Application December 19, 1951, Serial No. 262,456

1 27 Claims.

This invention relates to an apparatus for effecting discharge of solid material from the bottoms of containers therefor and, more particularly, to an improved means for controlling wherein the rate of application of pressure pulses to the liquid seal is automatically controlled by the height of the material in the furnace.

Another object of the invention is to provide the discharge of material from shaft furnaces. 5 an improved shaft furnace discharging meansmas An object of the invention is to provide an defined above and in which a column of iq (1 improved apparatus for effecting periodic disis provided externally of the liquid seal and comcharge of solid material from the bottom of a municating therewith with the said pressure shaft furnace, bin or other container for the pulses being applied periodically to the said colmaterial, thet saidthappariatulslhaviglilg tno moving1 um (iii (liquid tillers)? (sailing thet lattelrt ti; :hct parts contac ing e ma era so a wear an asap n ore ec g sc argeo ap o e .maintenance are reduced to a minimum. solid material which has gravitated from the fur- Another object of the invention is to provide nace into the said liquid seal. an improved apparatus for effecting periodic dis- An additional object of the invention is to procharge of solid material from the bottom of a vide an improved shaft furnace and discharge shaft furnace, bin or other container therefor means as defined above wherein the presence or wherein the discharging action is effected by absence of said material adjacent the bottom of periodic pulses of fluid pressure with the periothe furnace and the temperature of the region dicity of the pulses being automatically controlled automatically control the operation of the disby the height of the material in the container. charge means.

A further object of the invention is to provide The invention further resides in certain novel an improved apparatus for effecting discharge features of the construction and arrangements of solid material from a structure in which the of the parts of the apparatus in which the invenmaterial gravitates into a liquid seal at the bottom tion is embodied, and further objects and advanthereof and from which the material is perioditages of the invention will be apparent to those cally ditzscltliarged1 by cyclic pulses of pressure sklillled in tine afttfo whiiclhit pertains froitn an: appied 0 he sea o owing escrp on o e presen pre erre An additional object of the invention is to proembodiment thereof which is described with refvide'a shaft furnace for heating and/or induraterence to the accompanying drawings in which: ing discrete bodies of mineral solids, for example, Fig. 1 is a front view of a shaft furnace empellets of iron ore concentrates, with an improved bodying the invention, portions of the structure discharge means for the bodies, which means is being broken away and others shown in section so constructed and arranged that it eliminates to more clearly illustrate the novel features; dust and gas losses from the bottom of the fur- Fig. 2 is a fargmentary view taken substantially i it? 12? 2&2?! if ht"; it.iiriifi fie fiiifttitti 215th? rom, sno a ag or y es other large objects, has no moving mechanical side elevation with certain of the associated parts parts contacting the bodies, and is easily conshowninsection;

trolled to provide a wide range of discharge rates. Fig. 3 is a longitudinal sectional view through A more specific object of the invention is to 40 thenovel discharging apparatus per se illustratprovide an improved material discharging means ing the latter in operation discharging discrete for a shaft furnace in the form of a liquid seal bodies or pellets of 1iitilid mlateriizil; andin diagram for the bottom of the furnace to whichpulses Fig. 4 is a simp ed so ema c wir g of fluid pressure are periodically applied for ca'us- 0f t e trol i ui v nin p ration 01' th ing displacement of a portion of the liquid and discharging apparatus. of the material from the furnace, the construc- Control of the discharge of solid materials from tion being such that only a small amount of liqthe bottoms of bins'or other containers therefor uid is exposed to the material descending from may be effected by a wide variety of different the furnace so that danger from rapid generation apparatus when there is no problem of maintainof excessive vapor pressures as the result of sliping an air or gas 8 at e Point Of dischargeping or bridging in itshe Ignace is avoided, and zv g pfw sh t tif); sjfuy t d schairg chili: any genera e vapor rea yre ease ma er a ram e cm 0 a s we ure w A further object of the invention is to provide it is n ned. While at t e same time maintainan improved shaft furnace having a discharging I ing a gas tight seal at this point, many conventneans as defined in the preceding paragraph and 5 5 tional discharge controlling devices, such as con ventional valves, conveyors, and the like, are not satisfactory. The problems incident to controlling discharge while preserving a gas seal are especially acute when the structure in which the material is contained is a furnace, such as a shaft furnace, from which a portion of the contents, in the form of discrete bodies of relatively hard, solid material, must be periodically discharged without release or leakage of the gas pressure in the furnace. Therefore, the present preferred embodiment of the invention is here illustrated and described as incorporated in such a shaft furnace for heating discrete bodies of mineral solids. It is to be understood, however, that the invention is not limited to this specific embodiment, but that it may be employed for controlling discharge of solidmaterial from bins or other containers as well as from shaft furnaces.

The illustrated embodiment of the invention comprises a shaft furnace, generally designated Ill, having a shell H and a lining of refractory material l2 supported by suitable columns i3 and horizontal members H. In the form shown, the outside configuration of the furnace, in horizontal cross section, is substantially rectangular and it is divided transversely by. a, vertically extending partition wall l5 of refractory material, thus forming two independent compartments or shafts l6 and I1 respectively, each of which is substantially square in horizontal cross section. Each of the shafts or compartments I5, I! merge at the bottom thereof into downwardly tapering hopper-like portions l8 and I9, respectively, which are individually connected with separate discharging mechanisms 20 and 2| operating, as hereinafter described, to periodically discharge a portion of the material from the bottom of each of the shafts.

The furnace I0 is intended to operate under gas pressure greater than atmospheric and hence is provided with a gas collecting and exhaust hood 22 extending along the front and back of the furnace adjacent the upper edges thereof and connected with a suitable exhaust means, not shown, for withdrawing the air and other gases issuing from the top of the furnace. Material to be heated in the furnace is charged thereto by a suitable conveying means moving over the top of the furnace to deposit the material substantially uniformly therein, the charging means preferably being combined with a movable cover so that the gas pressure may be maintained in the furnace. Suitable means, not shown, for supplying heated and/or unheated air or other gases to the furnace are also provided for effecting the desired heating of the material within the furnace. These structures for feeding the furnace and for supplying air or other gases thereto do not form a part of this invention and hence will not be described in detail since they may take any conventional form.

The furnace here illustrated and described is primarily intended for use in heating discrete bodies of mineral solids which may, for example, be substantially spherical pellets of iron ore concentrates and which are to be indurated, but preferably not fused, by heating. Consequently, the rate of movement of the bodies through the furnace must be carefully controlled so that they will be heated to the proper temperature. This, in turn, requires that the rate of discharge be correlated to the quantity of material within the furnace at any given time, and also preferably to the temperature of the material.

In order to determine the quantity of material in the furnace, each shaft or compartment I! and i1 is provided adjacent the top thereof with spaced means adapted to provide a signal in response to the presence of material adjacent thereto. Since in the preferred embodiment, the bodies which are to be heated in the furnace are concentrates of iron ore, thesebodies are electrically conductive and hence the material sensing means are here shown in the form of elec trodes 23, 24, 25 and 26 in chamber [6 and 21, 2'.

- 29 and 30 in chamber H. The electrodes 23 and 21 are longer than the other electrodes and are adapted to be connected with the shell II or otherwise grounded to provide a common ground or return for the material sensing system. The electrodes 24 and 28.extend into the shafts i6 and I1 equal distances and represent the lowest level to which the discrete bodies or pellets should be allowed to fall during normal operation of the furnace. The electrodes 25 and 29 are similarly of equal length and are shorter than the electrodes 24 and 28, while the electrodes 26 and 30 are likewise of equal length and still shorter than the electrodes 25 and 29. The electrodes are each mounted by suitable supporting brackets, such as 3i, 32 adjacent the lining l2 of the furnace wall. The sizes of the electrodes are exaggerated in the drawings for the sake of clarity,

but it will be understood that the electrodes are relatively small and do not interfere with the normal movement of the material within the furnace. More than one set of electrodes may be provided in each of the shafts or compartments 16, ll, if necessary or desired, two such sets being shown diagrammatically in Fig. 4, which represents a schematic diagram of the electrical control circuit in which the electrodes are connected.

The lower tapered hopper-like portion l8, I! of each shaft or compartment of the furnace is provided with temperature responsive means 33, 33' and 34, 34', respectively, which are preferably in the form of thermocouples for sensing the temperatures in these portions of the furnace. Also, within the tapered hopper-like portions l8, IQ of the furnace are material sensing means 35 and 36 which may be of any suitable construction but preferably comprise a member, movable in response to contact therewith of pellets or the material in the furnace, for operating an electrical contact or contacts. Such devices are conventional and may be of the type sold for use in storage bins and like installations. The connections of the electrodes 23-30, and of the electrical contactsoperated by the thermocouples and the material responsive means 35 and 36 are illustrated in Fig. 4 and will be hereinafter described in detail.

As mentioned above, the shafts or chambers I6, I! are identical and are equipped with identical devices so as to, in effect, be two independent furnaces. This is considered preferable to, 'a single chamber or shaft of larger size in order that the heat may reach the bodies or pellets uniformly throughout. The invention is illustrated as embodied in such a multiple shaft furnace to demonstrate its adaptability thereto, it being understood that more than two shafts or chambers and associated discharge devices may be employed if desired. Obviously, therefore, the discharge control means 20 and 2| are identical and hence only one will be described in detail.

Referring now to Figs. 2 and 3 of the drawings, it will be seen that the discharge control means 28 comprises two vertically extending chambers or compartments 31 and 38 which communicate with each other only adjacent the bottoms thereof, the compartments being separated throughout the majority of their heights by a vertically extending wall 38. The top of the compartment or chamber 31 is in direct alignment and communication with the bottom of the tapered hopper-like portion 18 of the furnace shaft 16 so ing a vertically extending column of liquid. As

illustrated, this means is in the form of a cylindrical vessel providing a chamber 48 communicating adjacent the lower portion thereof with the lower portion of the discharge means 28 through a conduit 4|. The conduit 4| enters the discharge means 28 at a location which is preferably directly below the vertical wall 39 and in such a manner that the flow of liquid from it is substantially tangential to the course of flow of the pellets or other solids from chamber 31 and is directed toward the chamber 38. As will be clearly apparent from Figs. 2 and 3, the lower portion of the chamber 31 is preferably arcuate above the connection or conduit 4| with this arcuate wall terminating coextensive with the inner end of the conduit.

Water is supplied to the chamber 48 through a pipe 42 which is connected adjacent the top of the chamber, the flow of water through the conduit 42 being controlled by a solenoid operated valve 43 and a check valve 44, the check valve 44 being preferably interposed between the solenoid valve 43 and the chamber 48, so as to prevent reverse flow of water from the chamber and into the pipe 42. Extending into the chamber 48 from the top thereof are electrodes 45 and 46, electrode 45 having a length such as to at all times contact the water within the chamber 48 while the electrode 46 is in contact with the water in the chamber only when the latter has reached, or substantially reached, its maximum level therein. The electrodes 45 and 46 operate in a manner hereinafter described to control the operation of the solenoid valve 43, thereby controlling the application of water to the mechanism. The chamber 48 is also preferably provided with a sight glass 48a to indicate the water level in the chamber 48. a

It will be apparent from the construction thus far described that when the valve 43 has opened,

water from the pipe 42 can flow into the chamber 48 and will pass through the conduit or connection 4| into the compartments 31 and 38 of the discharge means 28 mixing with any fines therein to form a slurry or suspension thereof. The water will rise in the chamber 48 until it contacts the upper electrode 48 at which time a circuit will be completed, causing the valve 43 to close. The air within the compartment 48 is exhausted through a pipe .41 under control of a valve 48. The water and fines within the compartments 31 and 38 will seek a level commensurate with the level in the chamber 48 and the air or gas pressure in the furnace. That is to say, the water and fines will rise in the chamber 38 to a point substantially adjacent the open top thereof while the level of the water and lines in compartment or chamber 3! will stand at a lower level due to the pressure of the gasin the furnace. In other words, the head of water in the chamber 48 is sufficient so that'the lower edge of the wall 88 is completely submerged, with the result that the water and fines in chambers 81 and 38 comprise a liquid trap or seal for the furnace with the pellets or other solids from the furnace submerged therein.

The vessel which provides the chamber 48 is also provided, adjacent the top thereof, with a second pipe 49 to which fluid under pressure may be periodically applied under control of a solenoid operated valve 58. The operating member of the valve 88 is physically connected with the valve 48, so that when the valve 58 is open, the valve 48 is closed, and conversely. The pipe 48 is connected with a source of fluid under pressure, preferably air pressure, the pressure of which may be in the order of lbs/sq. inch. The construction is such that, when the valve" is opened and the valve 48 closed, the fluid pressure rapidly applied to the chamber 48 through the pipe 43 acts upon the water in that chamber. displacing the latter in the form of a piston. This piston of water acts through the conduit 4| upon the liquid seal and the bodies or pellets P in the discharge means 28 to provide a rising current in the liquid of sufficient velocity to displace the said bodies or pellets P vertically upwardly so that they flew from the discharging means over the lip or edge ii of the outer wall thereof, see Fig. 3. The height of this discharge lip or edge may be made adjustable by employing a separate plate adjustably connected to the outer wall of the chamber 38.

The fluid pressure exerted upon the water in the chamber 48 acts for a relatively short interval of time so that it is in the nature of a pressure pulse. -The pressure is terminated by closing of the valve 58 and opening of the valve 48, whereupon water is again supplied to the chamber 48 from the pipe 42 replacing that which has been displaced so that the cycle may then be repeated. The quantity of water displaced in each cycle is never sufficient to break the seal or trap for the air or gases in the furnace, so that the air or gas pressure therein is never lost through discharge of the material.

The intervals between applications of pulses of fluid pressure to the chamber 48 are so proportioned as to allow enough time for the chamber 48 to fill with water, the minimum duration of this interval being determined by the pressure of the water source and the dimensions of the various parts of the apparatus. By way of example. but without limitation thereto, one satisfactory operation employed pressure pulses having a duration in the order of /2 second, the pulses being separated by intervals of from seven to fourteen seconds depending upon the desired rate of discharge of the material. The control of the application of pressure pulses to the system may be manually effected, but is preferably automatically controlled as hereinafter described.

The pellets P or other material discharged from the chamber 38 as the result of the pulses of pressure applied to the discharging mechanism 28 flow over the top or discharge lip 5| into an inclined chute 52 which directs the pellets to the upper end of a screening means 53. This screening means is preferably resiliently supported at an incline by springs 54,,55 and cables or rods 53, 51, and the screen is vibrated by a motor 89 driving a shaft 60 supported on the sides of the screen and provided with eccentrics 6|, see Fig. l. The screening means 53 preferably is provided with two spaced, perforate screening portions 62 and 63 although a greater or lesser number-may be employed if desired. Bodies or pellets P having a size larger than the openings in the screen 62 and 63 move over the tops therea of onto a conveyor 64, which is preferably an endless belt troughed in the conventional manner and driven by an electric motor 65. The fines or screenings from the screening means 53 move along the inclined imperforatelower surface 66 to a funnel-like member 61 connected by a conduit 68 leading to a suitable point of disposal.

The material discharge means 2! is identically constructed and operates in like manner to that designated 20, being provided with a solenoidoperated valve 69 for the water supply and solenoid-operated valve 10 for controlling the application of the pulses of fluid pressure thereto. The pellets from the discharge means 2| likewise flow therefrom through a chute which is similar to the chute 52 and merges with the lattcr for directing the pellets or other bodies onto the screening means '53 as will be apparent from Fig. 1.

Referring now to Fig. 4, it will be seen that electrical power is supplied to the control circuit for the apparatus from power lines LI and L2 through disconnect switches H, 12 and 13, which may be individually operated but preferably are ganged for simultaneous operation. The switches (I and 13, when closed, connect the power line Ll to the main supply-wires 14 and 15 of the circuit, while closing of switch 12 connects power line L2 to the main supply wire 16 of the circuit. The portion of the circuit to the left of wire 16 in the diagram represents the controls for the discharge means 20, while the portion of the circuit to the right of wire 16 represents the controls for the discharge means 2!.

Since these two portions of the circuit are identical, only one will be described in detail.

The power wire 14 is connected to one terminal of the solenoid for the water valve 43, the other terminal of which is connected, in series, through the normally closed contact WRI of a relay WR to a wire 11 connected with the power wire IS. The wire 11 is also connected with the electrode 45 in the chamber 40, while the electrode 46 in that chamber is connected to one terminal of the coil for relay WR, the other terminal of this relay coil being connected to the power wire 14. It will therefore be apparent that, when the water in the chamber 40 drops below the bottom of the top electrode 46, the circuit for the relay WR will be open so that the contact WRl'is closed, thus energizing the solenoid valve 43, opening the latter and allowing water to enter the chamber 40. When the water in the chamber 40 reaches the electrode 46, it closes the circuit between the electrodes 45 and 46, thus energizing relay WR causing the latter to open its contact WRI, thereby deenergizing the solenoid valve 43 so that the supply of water to the chamber 40 is terminated.

The power for the material sensing electrodes 23-26 is derived from a transformer T, the pri- Y mary 18 of which is connected between the power wires 14 and 16. The secondary 19 of this transformer has one terminal thereof connected with the shell II of the furnace and hence with the 8 electrode 22. The other terminal of the secondary 1915 connected by a wire '80 to one terminal of a relay DH, the other terminal of which is connected with the upper electrode 26. Also connected to the wire is one terminal of a coil of a relay LH, the other terminal of which is connected with the middle electrode 25. In addition, a wire 8| connects the said other terminal of the coil of relay LH to a stationary contact 82 which is adapted to be bridged with a contact 83 by the movable contact LI-Il of relay LH when the latter is energized. Since contact 83 is connected with the electrode 24, closing of contact LHI connects electrode 24 to electrode 25 for a purpose which will hereinafter be apparent.

As mentioned above, the valves 48 and 50 are connected for simultaneous actuation by the solenoid for the latter valve. In the illustrated embodiment energization of this solenoid is under the control of timing devices which are adapted to periodically open the valve 50, and simultaneously close the valve 48, for a predetermined relatively short interval of time with the intervals between such operations being of considerably longer duration. These timing devices are preferably motor drivenand are adjustable to provide contact operation after preselected time intervals. Since these devices are of conventional construction, the details thereof are not here set forth, the devices being schematically illustrated as motor driven and are designated TF, TN and T0 in Fig. 4. The timing device T0 is that which controls the interval during which the solenoid for valve 50 is operated to supply fluid under pressure to the water in the chamber 40, thus effecting discharge of a portion of the liquid in the mechanism 20 and of the solid material therein. The timer TN determines the length of interval between successive operations of the solenoid for valve 50 when the level of material in the furnace is in contact with the electrode 25. The timer TF provides for a more rapid operation of the discharge means by controlling the interval between operations of the valve 50 when the level of the material in the furnace engages the electrode 26.

In addition to the control exercised by the timers TO, TN and TF, the solenoid-operated valve 50 is also governed in its operation by the temperature in the lower portion or hopper I! of the furnace as sensed by the thermocouples 33 and 33. Thus, the absence of pellets in the said lower portion of the furnace, due to bridging or the like at a higher elevation, permits the air supplied to the bottom of the furnace to directly contact the thermocouples thereby cooling the latter so that they prevent operation of valve 50. The presence or absence of material in lower portion of the furnace; that is, in the tapered or hopper-like portion I8 acts through the device 35 to permit or prevent actuation of the valve 50 under control of the timing means. Furthermore, the valve 50 is controlled so that it cannot be operated unless the motor 65 for the conveyor 64 is in operation, thereby insuring that the material discharged from the furnace will be removed from the point of discharge.

The above-mentioned controls can be traced in the diagram comprising Fig. 4 by observing that the power wire 14 is connected with a wire 84 which is adapted to be connected with one terminal of a coil for a motor starter MS through a normally closed stop switch 34 upon operation of a manually actuated start button 85. The other terminal of the coil for th starter MS is connected with the power wire 19. Hence, when the button 95 is depressed, the motor starter MS is energized, closing its contacts MSI, M82. M89, M84 and M85. Closing of. the contact M89 provides a holding circuit for the starter MS about the push button 95 so that the latter may be released, Closing of the contacts M54 and MSI provides an energizing circuit for the motor 95 through the wires 95 and 91 connected with the power wires I4 and 19 respectively. Closing of the contact M82 completes a circuit from the wire 94 to one terminal of a contact of the switch 39 which is closed by the pressure of material in the hopper portion it o! the furnace and opens when this portion 01' the furnace does not have material therein. From the contact 95, this circuit continues to one terminal 01' the solenoid valve 59, the other terminal of which is adapted to be connected with a wire 99 upon closing of a contact YI of relay Y.- Ihe wire 89 is connected with a stationary contact 99 in thetiming mechanism TO and the latter is adapted to be engaged by a movable contact 99 on operation of the timer T0, thus completing a circuit therethrough and through wires 9i and 92 to the power supply wire 19. Connected in parallel about the contact Yl are contacts 33a and '11, which are normally open but which are closed by the thermocouples 99 and 99', respectively, when the temperature in the hopper portion I9 oi the furnace attains a predetermined value by the presence of previously heated pellets therein.

The contact 93a is adapted to operate in conjunction with a normally closed contact 9911, while the contact 93'a is adapted to operate in conjunction with a normally closed contact "'12. The contacts 39a, 39b and 3'0, 39'!) are normally contained within conventional potentiometer type mechanisms which are connected with the thermocouples 39 and 99' for indicating the temperatures sensed thereby and for operating the said contacts in response to those temperatures. The normally closed contacts 99b and ll'b are connected in parallel between the power supply line 19 and one terminal of the coil for relay Y. The other terminal of this coil is adapted to be connectedwith a wire 99 by operation of a manual push button 94 and this wire 99 is connectible with the wire 84 through closing of the contact MSI of the motor starter MS. The wire 99 is also connectible with the relay Y through closing of r the contact Y2, thus providing a holding circuit about the switch 94. In addition to the contacts Y2 and YI the relay Y has a contactYl operating similar to the contact YI for controlling the operation of the solenoid valve III for the pressure pulses in the discharge control means 2|.

In addition to the movable contact 99, the timer TO has movable contacts 95 and 96 connected with the wire 9|, contact 95 being normally open but adapted to engage a stationary contact 9'! connected with one terminal of the motor for the timer, the other terminal of which is connected by a wire 99 to the power wire I4. The movable contact 96 is normally engaged with a stationary contact 99 which is, in turn, connected by a wire I90 to one terminal each of the motors for the timers TN and TF. The other terminal oi the motor for the timer TN is connected by a wire II in a circuit adapted to be closed by a normally open contact XI of a relay X, the circuit continuing through the normally closed contact DHI of the relay DH to the power wire I4. The other terminal of the motor for the timer TF is adapted to be connected by closing or the normally open contact QI oi a relay Q to a wire I92 connected with the power wire I4. The wire 92 is also connected to the movable contacts I99 and I94 01' the timer TN and to the movable contacts I05 and I99 01' the timer TF. The movable contacts lil4 and I99 are adapted, respectivey. to engage stationary contacts I91 and I99, which are connected to each other and to the contact 91 of timer TO by a wire I99. The contacts I99 and I95 are adapted te-respectively engage stationary contacts I I9 and III which are connected to the wire IIIIl leading from the contact 99 to one terminal each of the motors i'or the timers TN andTF.

The aforementionedrelay DH has a normally open contact DH2 which is adapted, when closed, to provide a circuit from the wire 14 to one terminal of the coil for relay Q, the other terminal of which is connected with the power wire 16 by a wire I I2. The relay LH has a normally open contact LH2 which is adapted, when closed, to provide a circuit from the power wire I4 to one terminal of the coil for relay X, the other terminal of which is connected with the power supply wire I9 through a wire II9. Bridged about the contact LHZ is a manually operable switch I I4, preferably of the push button type, which is provided to ef- Iect manual starting of the discharge apparatus, as will be hereinafter described.

In addition to the aforementioned power supply ior the control circuit, a separate power supply is preferably provided for an alarm circuit, in order to insure that a failure of the conventional power supply will not interrupt the alarm circuit.

This separate power supply for the alarm circuit is provided from power lines L3 and L4, which are connected through fuses H5 and H5 to the main wires I I1 and I I 9 of the alarm circuit. Connected with the wire III is a wire II9 which provides a circuit through the normally closed contact X2 01' relay X to a lamp I29 which is preferably white in color, the circuit continuing through wire I2I to the wire II9. Connected in parallel with the lamp W, between the wires H9 and I2 I, is a circuit for a lamp I22 which is preterably green in color, this circuit being controlled by the normally open contact X9 of relay IX and th normally closed contact Q2 of relay Q. Also connected between the wires I I9 and I2I is a lamp I29, preterably'red in color, the circuit to which is controlled by the normally open contact Q9 of relay Q. 7

Connected with the wire II! is a wire I24 which is adapted to be connected with a wire I25 upon closing of the normally open contact DH3 of relay DH. The wire I25 is connected through a normally closed contact Z I of a relay Z to one side of a suitable alarm, here shown as a bell I26, the other side of this alarm being connected to the power wire I I9 0! the alarm circuit. One terminal of the coil for relay Zeis connected by wire I 21 to the power wire II9 of the alarm circuit, while the other terminal 0! this coil is adapted to be connected with the wire I25 through a switch I28 which may be of the push button type. Between the switch I29 and the coil of relay Z is a connection for a circuit adapted to be closed upon operation of the normally open contact Z2 of relay Z, this circuit continuing through a wire I29 and the normally closed contact X4 of relay X to the power wire III of the alarm circuit. In addition wires I25 and I29 are connected so that contact Z2 provides a holding circuit around switch I29. The wire In is also connected to a wire I and the wire H9 is connected to a wire I9I to provide power tacts X2 and X4.

. 11 I for the signal lamps I30a, I32 and I33 of the discharge means 2|, these lamps being similar in nature and operation to the lamps I20, I22

and I23.

In addition to the aforementioned instrumentalities in the control and alarm circuits, the power lines L3 and L4 of the alarm circuit may be provided with suitable disconnect switches, if desired. Also the main control circuit and the alarm circuit may be provided with various protective devices and other conventional expedients which have not here been illustrated in order to simplify the disclosure.

In operating the apparatus, material to be indurated by heating in the furnace, for example, pellets of iron ore concentrates, are charged into the top thereof and heat is supplied to the interior of the furnace through conventional means not shown. The pellets or other material form a continuous column in the furnace extending from the bottom to the top with the previously indurated portion of the material disposed within the chambers 31 and 38 of the discharge means so that the water supplied to this portion of the apparatus provides a liquid seal for the bottom of the furnace. The pellets are maintained at a level in the furnace which is preferably intermediate the lower ends of the electrodes 24 and 26, so that the said pellets are in contact with the electrode 25. Consequently, when the disconnect switches II, I2 and I3 are closed, a circuit is completed from the shell of the furnace through the secondary of the transformer I9 and the coil of relay LE to the electrode 25 and through the pellets to the electrode 23 which is in electrical engagement with the shell II. The relay coil LH will therefore be energized causing it to close its contacts LHI and LH2. Closing of the contact LHI completes a circuit through the electrode 24 and the pellets to the electrode 23, thus maintaining the relay LH energized, even though the level of the pellets should subsequently fall below the lower end of electrode 25/ Closing of the contact LH2 energizes the coil of the relay X causing the latter to operate its contacts XI and X3 to closed positions and open its con- Opening of the contact X2 extinguishes the white signal light I20, while the closing of contact X3 illuminates the green signal light I22. Opening of the contact X4 breaks the circuit to the alarm bell I26 preventing operation of the latter.

The illumination of the green signal lamp I22 indicates that the level of the pellets in the furnace is proper for discharging operations to occur and if there are no obstructions to movements of pellets through the furnace, the pellets in the lower part-of the furnace will have also operated the switch 35 to closed position. Also, the presence of heated pellets adjacent the discharge will have affected the thermocouples 33 and 33' so that the contacts 33a and 33'a. are closed and contacts 33b and 33'b are opened. It will also be understood that the initial closing of the disconnect switches 'II, I2 and I3 will have caused the chambers such as 40 to fill with water due to the completion of the circuits for the valves 43 and 69 through the contacts of their associated relays WR, the valves being held open until the water rises sufiiciently within the chambers 40 to close the circuit between the electrodes such as 45 and 46, as previously described.

Although the apparatus is now prepared for discharging operations, such discharge cannot begin until the conveyor 64 has been placed in 12 operation. Consequently, the operator now depresses the motor start button 05, thus completing a circuit through the latter energizing the motor starter MS, so that the latter closes .lts contacts MSI, MS2, M33, M84 and M85. Closing of the contacts M34 and M35 energizes the motor 05, thus placing theconveyor 64 in operation for removing any discharged pellets. Closing of the contact M83 completes a holding circuit therethrough for the motor starter MS so that the push button switch 85 may now be released and the starter MS will remain energized. Closing of the contact MSI completes a circuit therethrough for control of the discharge means 2|, while closing of the contact MS2 completes a circuit therethrough for control of the dis-' charge means 20. Since these devices are identical and the control circuits are the same, only the last-mentioned circuit will be described.

The circuit closed through the contact M82 by operation of the motor starter MS continues through the now closed switch 35, which is responsive to the pellets in the hopper or lower portion III of the furnace, and through the temperature controlled contacts 33a and 33'a which are now closed due to presence of properly heated pellets in the hopper portion of the furnace. From this point the circuit continues through the wire 88 to the stationary contact 80 of the timing mechanism TO. The previously mentioned closing of contact XI completed a circuit from the wire I4 through the normally closed contact DHI and the now closed contact XI to the wire I0 I, which circuit continues through the motor for the timer TN and the wire I00 to the engaged contacts 96, 99 of the timer TO and from the latter through the wires 9| and 92 to the power wire I6. Consequently the timer TN, which provides the timing of the interval of normal duration between operations of the discharge means, is energized and begins its timing operation.

When the time interval for which the TN timer has been set has elapsed, it will operate its contacts I03 and I04 into engagement with the stationary contacts H0 and I01, respectively. The circuit completedthrough the contacts I03 and H0 maintains the timer 'IN in operation, while the engagement of the contacts I04 and NI provides a circuit energizing the timer TO. This last mentioned circuit extends from the wire I4 through the wire 98 and the motor of the timer TO to the wire I09, thence through contacts I01 and I04 to the wire 92 which is connected with the power wire I6. Consequently the timer T0 is now placed in operation and moves its contacts and 95 to circuit closing engagement with the stationary contacts 89 and 91, respectively. Simultaneously the TO timer moves contact 96 from engagement with contact 99 but-timer TN is not immediately stopped since its circuit is now completed through contact I03. This ensures that the timer TN will not stop with its contacts I03 and I04 in circuit closing positions but will operate until contact I03 moves from engagement with contact IIO. Closing of contacts 95 and 91 of timer TO provides a circuit for continuing operation of this timer through its cycle, while closing of the contacts 89 and 90 completes the previously mentioned circuit for the solenoid or air valve 50, so that the latter is now energized, moving it to open position and simultaneously closing the valve 48.

Consequently, fluid under pressure, which in this instance is air pressure, is supplied to the l3 top of the chamber 46 for an interval determined by the timer TO. This pressure pulse acts upon the water within the chamber 40 moving the latter, in the nature a piston, into the discharge means 20 and rising therein displaces a part of the pellets and liquid therefrom and from the chamber :8 into the chute 62. The discharged pellets then travel over the vibrating screen means 53 to theconveyor 64 and are carried to the chamber 60 is relatively short and may, for

example, be in the order of one-half second. This time interval is determined by the timer TO which is so set that, when the predetermined interval has elapsed, the timer will have moved to a position such that its contacts 90, 95 and 96 have been restored to their positions shown in Fig. 4 operation of the timer TO having continued after contacts IMand ll! of timer TN separated due to the circuit through contacts 95 and 91 of the timer TO. When the contacts of timer T0 are again restored to their initial positions the circuit through the solenoid valve 60 is opened at the contacts 69, 90 so that the valve 50 closes and the valve 46 opens. This permits the chamber III to again fill with water, since the chamber is now exhausted to atmosphere and the previous displacement of water from the chamber has exposed the electrode 46 therein so that the relay WR is deenergized. Consequently, a circuit is now completed through contact WRI energizing the solenoid-operated valve 43 so that the latter again opens and water enters the chamber III until electrode 46 is again contacted as will now be understood. This filling of the chamber In is normally accomplished in much less time than the interval between successive pressure pulses, so

' that the chamber 40 is again filled with water in preparation for a new discharging operation well in advance of the application of the next pressure pulse.

When the T0 timer contacts are restored to their initial positions after the discharging operation, the circuit to the motorfor the TN timer is reestablished through the contacts 96, 99. Therefore, timing of a new interval begins under control of the TN timer. When this interval has elapsed, the contacts I03, IOI of the TN timer will again move to circuit closing positions, as previously described, thus again completing the circuit to the TO timer. As before the TO timer will operate the valve 50 for a predetermined short timeinterval thus applying a pressure pulse to the chamber 40 and hence causing another discharge of pellets from the furnace.

. The aforementioned alternateoperations of the TO and TN timers, eflecting periodic discharge of material, normally continue without interruption solong as material is supplied to the furnace at substantially the same rate as that at which it is removed by the discharge means and so long as the temperature within the furnace remains proper and there is no bridging or hang-up of the material therein. However, in the event the material be supplied at a faster rate than that at which it is removed, the level of the material in the furnace will rise until the electrode 26 is con- .tacted and this will then complete a circuit the circuit to the green signal lamp I22, while closing of the contact Q3 completes the circuit to the red signal lamp I23.

' Closing of the contact DH! completes a circuit through the latter and wire I to the normally closed contact ZI and thence to the alarm bell I26, the circuit being completed from the latter to the alarm wire H6. Therefore the alarm I26 is sounded when the level of the pellets rises into engagement with the upper electrode 26 so that the operator is apprised of the factthat the rate of charging is excessive and may take steps to correct the same. If desired, the alarm bell I26 maybe removed from the circuit by operating the push button switch I26 since this completes a circuit through the relay Z, energizing the latter, thus opening the contact ZI in the circuit of the bell I26. The energization of the Z relay also has closed the contact Z2 so that the Z relay is maintained energized through a circuit extending from the wire III through the wire I24, contact DB3, wires I25 and I 29 and the now closed contact Z2, relay Z and the wire I21, which is connected with power wire I II of the alarm circult.

Closing of the contact QI completes a circuit therethrough to the motor of the timer TF, this circuit being completed through the wire I I0, and the contacts 96, 96 of the timer TO, and wires 9|, 92 to the power wire I6. Consequently, the TF timer is now energized and, after the time interval for which it is adjusted, operates to move .lts contacts I05 and I06 to circuit closing relationship with contacts III and I08, respectively. Closing of the contact I 06 to the contact I06 completes a circuit through the wire I09 to the motor of the timer .TO, energizing the latter so that it operates to move its contacts and 95 to circuit closing position and contact 96 to circuit opening position. Consequently, the energizing circuit for the TF timer through contacts 96 and 69 is broken. Nevertheless, the timer TF will continue to operate until its contacts return to open positions by virtue of the circuit therefor through its contacts I06 and III. Closing of the contacts 62 and 60 energizes the solenoid valve 50, as previously described, thereby applying a pulse of fluid pressure to the chamber 40 thus effecting discharge of material. The closing of contacts 95 and 61 maintains the timer T0 in operation until its contacts return to the positions illustrated whereupon the closing of contacts 69, 90 again energize the timer TF starting a new cycle of operations. i

Therefore, the operation of the apparatus is now substantially the same as has been previously described for the timers TN and TO except that the interval between repeated pulses of fluid pressure is now determined by the timer 'IF instead of by the time TN. The timer 'I'F is preferably so adjusted that its rate of operation is more rapid than that of the timer TN and may, for example, be twice as fast as the timer TN. Consequently, the periodicity of the pulses of fluid pressure is increased with the result that the rate of material l discharge is increased so that the level of the material in the furnace will tend to drop if the charging rate is maintained constant.

When the material in the furnace has dropped below the lower end of electrode 26 but is in contact with the electrode 25, the circuit through the relay DH will be broken so that this relay is de-energized, thus causing the contact DHI to close and the contacts.DH2 and DH3 to open. Consequently, the TN timer will against be energized. Also, the Q relay will be de-energized,

- thus breaking the circuit to the timer TF and the red signal light I23 and establishing a circuit to the green signal lamp I22. Likewise, the circuit to the alarm bell I26 is opened, since the contact DH3 is now opened. In the event the alarm bell had been previously removed from the circuit by operation of the relay Z, the opening of the DH3 contact will also break the holding circuit for the Z relay de-energizing the latter, thus preparing the alarm bell for a new operation in the event the level of the pellets or other material in the furnace again rises to contact the electrode 26.

In the event the rate of discharge exceeds the rate of charge of material, the level of the material in the furnace will drop. If the level should fall below the lower end of the electrode 24, the circuit between the electrodes 23 and 24 will be broken thus de-energizing the relay LH so that the latter opens its contacts LHI and LH2. Opening of the contact LH2 de-energizes relay X, causing the latter to open its contacts XI and X3 and close its contacts X2 and X4. Closing of the contact X2 energizes the white signal lamp I20, while opening of the contact X3 extinguishes the green signal lamp I22. Opening of the contact XI breaks the circuit to the timer TN and hence to the timer TO so that discharge of material from the furnace is terminated. The closing of the contact X4 completes a circuit through the latter and the normally closed contact ZI, energizing the alarm bell I28 so that the latter will direct the attention of the operator to the fact that the furnace level is below its proper height. The alarm may be removed from the circuit by momentarily actuating the switch I28, .thus completing a circuit through this switch and the coil of the Z relay, energizing the latter so that the contact Zl is opened and the contact Z2 is closed. Opening of the contact ZI terminates energization of the alarm bell, -while closing of the contact Z2 maintains the Z relay energized.

When the level of the material in the furnace has been raised to again contact the'electrode 25, the LH relay will again be energized, closing its contacts LHI and LH2. Closing of contact LH2 will again energize the X relay re-'- establishing the circuit to the timer TN so that the discharge may again resume. Likewise, the signal lamp I20 will be extinguished and the lamp I22 will be illuminated and the circuit to neath the bridge continues to be removed at the usual rate. As a matter of fact, if the bridge be suiliciently large, the level of the material in the furnace may actually increase due to the continuous charge of material thereto. This will cause an even more rapid discharge of material from the furnace, since the electrode 26 will be contacted, thus bringing into action the rapid timer TF. This is highly undesirable and might result in damage to the furnace or injury to the personnel, in the event the hot material from a point higher up in the furnace should suddenly drop into the water of the water seal. The material responsive switch 35 has been provided to prevent such an occurrence, since it will open if there be no material adjacent this switch as would be the case in the event abridge of the material formed within the shaft of the furnace. Upon the formation of such a bridge and the resulting depletion of the material thereunder in the hopper-like portion I8, the opening of switch 35 will break the circuit to the solenoidoperated valve 50. Hence, even though the timers, such as TN, TF and TO, continue in operation, pressure pulses cannot be applied to the chamber 40 and hence discharge of material will be terminated until such time as material again accumulates in the hopper portion I8 of the furnace and closes the switch 35.

The thermocouples 33 and 33' provide an additional precaution against such an occurrence, since the absence of pellets adjacent thereto will allow the thermocouples to cool and cause them to operate to open the contacts 33a and N'a and close the contacts 33b and 33b. This ening of contacts 33a. and 33'a terminates operation of the discharge means since the circuit therethrough for the solenoid operated valve 50 is broken. Consequently, automatic discharge of the material is terminated.

Should material be in the lower portion of the furnace but at lower than a predetermined temperature so that automatic discharge of the material in the furnace is prevented by the above-mentioned opening of contacts 33a and 33a and closing of contacts 33b and 33b, the discharging action may be manually initiated by operation of the push button switch 94. Thus, with the conveyor 54 in operation, the contact MSI is closed and hence a circuit will be completed, upon operation of switch 94, from the wire 14 through wire 84, switch 84', contact MSI, wire 93, switch 94, and the coil of the relay Y to and through the now closed contacts 33b and 33'b. Therefore, relay Y is energized, causing the latter to close its contacts YI, Y2, and Y3. Contact Y2 provides a holding circuit for the Y relay so that the switch 94 may be released without de-energization of the relay. Closing of the contact YI provides a bridging circuit about the now open contacts 33a and '11 so that discharge of the material within the furnace is now effected under control of the timers TN, TF and TO even though the material is unheated or is at a lower temperature than that desired in the normal operation of the furnace. This discharging operation will, however, continue under control of the material responsive electrodes 24, 25 and 26, as previously described.

When the material within the furnace has reached the predetermined temperature for operation of the contacts 33a and 33'a to closed positions, the circuit through the latter to the timer TN will again be closed. Hence, normal 17 automatic operation of the discharge may be resumed in the event the level of the material within the furnace is sufficient to contact the level indicating electrodes as has been previously described. This restoration of the contacts 33a and 33'a to closed positions will have simultaneously opened the contacts 33b and 33'b, thereby de-energizing relay Y so that the previously described circuit which permitted discharge without control by the thermocouples is broken.

In the event it is desired to operate the discharge means when the level of the material is below the electrodes in the top of the furnace, this may be effected by actuating the manual switch Ill. This energizes the X relay which completes the necessary circuits for operation of the TN and T timers as will now be apparent. This mode of operation therefore enables the furnace to be substantially emptied of material and may be effected regardless of the temperatures of the material since push button 94 may also be actuated to by-pass contacts 33a and "'a in the event the material is below the predetermined temperature for operation of these contacts.

While one portion of the control and alarm circuits for operating one only of the discharge means has been described in detail, it will be apparentthat the other discharge means 2| opcrates for control of the discharge from the other shaft of the furnace in the same manner. It will also be evident that, although the illustrated embodiment discloses a furnace having two parallel shafts with two discharge means, a furnace having only one shaft and discharge means may be employed if desired or more than two shafts and discharge means may be utilized when greater capacity is desired. It will also be apparent that, in the normal operation of the apparatus, a liquid seal is at all times maintained forthe bottom of' the furnace so that air or gas pressure therein is not lost during discharge of the material. Moreover, there are no moving parts contacting the pellets or other material being discharged so that wear is reduced to a minimum. Furthermore, the discharging apparatus is not affected by the size of the material and hence can discharge both the lines which may develop in the operation of the furnace as well as the larger particles which are the unbroken discrete bodies or pellets P. Similarly, clusters of pellets which may occur can pass through the discharge means so long as they do not exceed the dimension between the lower end of the partition wall 39 and the bottom of the compartments 31, 38, thus enabling the discharge means to handle clinkers or fused material of larger size than that which can be normally passed through conventional grates or discharge plates. It will also be evident that, where the furnace is operating upon pellets or similar discrete bodies of mineral solids, the product issuing from the furnace is free of fines and dust and has been cooled to a point where it will not injure conventional conveyor belts, thus facilitating handling.

An important feature of the invention is the elimination of danger of explosions resulting from sudden generation of excessive gas or vapor pressure by highly heated material contacting the liquid of the seal in the discharge means. This hazard is eliminated not only by the provision of the aforementioned thermocouples and material responsive switches in the hopper-like portions I8 and I9, which prevent automatic discharge when "bridging" or "hanging" occurs in the furnace, but also by the novel design and proportions of the discharge means 20 and 2|. Thus it will be noted that the cross sectional area of the compartment 31 of the discharge means is very materially less thanthat of the furnace shaft and the depth of the liquid in the discharge means necessary to provide the gas seal is small compared to the height of the furnace. Consequently, only a small quantity of liquid is exposed to descending material at a given interval of time with the result that. even in the case of a "slip" or the like which might cause red hot solids to drop into the liquid, the quantity of such solids in contact with the liquid would be such that the amount of vapor generation would not cause a aserious explosion. Moreover, any sudden or excessive gas or vapor generation is easily and safely relieved through the chamber or compartmerit 38 comprising the discharge leg of the apparatus.

Although the invention has been illustrated and described with particular reference to its incorporation in a shaft'furniice for heating discrete bodies of mineral solids, it will be evident that the invention may be employed for discharging other materials from other receptacles or containers, as, for example, from bins or containers which are not shaft furnaces but in which it is desired to maintain an air or gas pressure without leakage or loss during discharge of the material therefrom. Also, although the liquid used for effecting the discharge and the seal is water, other liquids may be employed. Likewise, a means other than pulses of air pressure may be employed to provide the periodic piston like displacement of the water or other liquid from the chamber 40 with suflicierit velocity to effect lifting of the solids over the discharge lip. In view of these and other possible adaptations and modifications, the invention is not to be considered as limited to the specific details of construction here illustrated and described except as may be required by the spirit and scope of the appended claims.

Having thus described the invention, we claim:

1. In a shaft furnace for indurating discrete bodies of mineral solids, means providing-a liquid seal at the bottom of said furnace into which the indurated bodies move, the said means having a discharge opening spaced above the bottom thereof, means for periodically applying pressure to the liquid in said seal at a ratesuflicient to displace a portion of the liquid and the indurated bodies therein through the said discharge opening, and means to replace the portion of the liquid displaced throughthe discharge opening.

2. The combination as defined in claim 1 and further comprising means responsive to the temperature in the region intermediate the furnace proper and the said liquid seal providing means, and means actuated by said temperature responsive means for preventing the said periodic application of pressure to the liquid in said seal until the temperature of said region has attained a predetermined value.

3. The combination as defined in claim 2 and further comprising manually operable means for initiating the said periodic application of pressure to the liquid in said seal before the temperature of said region has attained the said predetermined value.

4. The combination as defined in claim 1 and further comprising means adjacent the lower portion of said furnace for sensing the presence 19 of the said bodies therein, and means responsive to said sensing means and operatively connected to said means for periodically applying pressure to said liquid seal for preventing operation thereof when no bodies are sensed.

5. The combination as defined in claim 1 and wherein the means for applying pressure to the liquid comprises means for applying air under pressure to said liquid, and means to periodically operate said applying means for an interval of short duration thereby providing a pressure pulse.

6. In a shaft furnace for indurating discrete bodies of mineral solids, means providing a liquid seal at the bottom of said furnace into which the indurated bodies gravitate, the said means having a discharge opening spaced above the bottom thereof, means for periodically applying pressure to the liquid in said seal at a rate sufficient to displace a portion of the liquid and the indurated bodies therein through the said dis,- charge opening. means for replacing the portion of said liquid displaced through the discharge opening, and means responsive to the level of solids in said furnace for controlling the cyclic pediodicity of the said application of pressure thereby controlling the rate of discharge from said furnace.

7. In a shaft furnace for indurating discrete bodies of mineral solids, means providing a liquid seal at the bottomof said furnace into which the indurated bodies gravitate, the said means having a discharge opening spaced above the bottom thereof, means providing a column of liquid external of said furnace'and in communication with said seal, and means for periodically applying pressure to the surface of the liquid in said column at a rate sufilcient to cause the latter to act as a piston for displacing a portion of the liquid of said seal and the indurated bodies therein through the said discharge opening.

8. The combination as defined in claim '7 and wherein the means for applying pressure comprises means for applying fluid under pressure to the surface of said column of liquid and time con-.

trolled means for operating said applying means with cyclic periodicity.

9. In a shaft furnace for indurating discrete bodies of mineral solids, means providing a liquid seal at the bottom of said furnace into which the indurated bodies gravitate, the said means having a discharge opening spaced above the bottom thereof through which the bodies can move only when force is applied thereto, means for applying fluid pressure to said liquid seal for displacing a portion of the liquid of said seal and the indurated bodies therein through said discharge opening, timing means operatively connected with said pressure applying means to control the duration of operation of the latter, and a second timing means operatively connected to ,means for periodically applying a pressure pulse to the liquid in said seal at a rate sufllcient to displace a portion of said liquid and the material from said furnace through the said discharge p nin 12. In a shaft furnace, means providing a liquid seal at the bottom of said furnace in which the material passing through said furnace is received, the said means comprising two chambers communicating adjacent their bottoms with the top of one of said chambers substantially aligned with the interior of said furnace and with the other of said chambers provided with a discharge opening adjacent its top, means providing a column of liquid externally of said chambers and communicating with the latter adjacent the bottoms thereof with the height of said column sufficient to cause the liquid in said chambers to stand at a height above the level of the communication therebetween, and means for periodically applying a pressure pulse to the surface of the liquid in said column at a rate suilicient to cause the latter to act as a piston for displacing a portion of said liquid and the material from said furnace through the said discharge opening.

control the intervals between operations of the 13. The combination as defined in claim 12 and further comprising means for supplying liquid to said column providing means, and means responsive to the level of liquid in said column for controlling said supplying means.

14. The combination as defined in claim 12 and further comprising means responsive to the top of the material in said furnace for controllin the cyclic periodicity of the said application of pressure pulses to the liquid in said column.

15. In a shaft furnace, means providing a liquid seal at-the bottom of said furnace in which the material passing. through said furnace is received, the said means comprising two chambers communicating adjacent their bottoms with the top of one of said chambers substantially aligned with the interior of said furnace and with the other of said chambers provided with a discharge opening adjacent its top, a closed vessel connected adjacent its bottom with said one chamber adjacent the bottom of the latter, a liquid supply pipe connected to said vessel for supplying liquid to the latter and to said chambers, the

,'height of said vessel being such that the level of the liquid in said chambers is above the communication therebetween thereby providing a liquid seal for the bottom of said furnace, and means for rapidly applying fluid under pressure to the liquid in said vessel thereby creating a rising current of said liquid of suflicient velocity to lift apportion of the material from said furnace through the said discharge opening. a

16. The combination as defined in claim 15 and wherein the means for applying fiuid under pressure to said vessel includes a fluid supply pipe connected to said vessel, a valve in said pipe, and timing means connected to said valve for periodically operating the latter.

17. The combination as defined in 'claim 16 21 and further comprising means responsive to the height of the material in said furnace, a second timing means for operation of said valve'at a different time interval than that effected by the first-mentioned timing means, and operative connections from said material height responsive means to said timing means for selective operation of the latter such that the first-mentioned timing means is effective to operate said valve when the material in the furnace is at a predetermined height and the second-mentioned timing means is effective for operation of said valve when the material in said furnace extends above said predetermined height.

18. The combination as defined in claim and further comprising temperature responsive means adjacent the lower portion of said furnace for sensing the temperature at that region, and means actuated by said temperature responsive means for preventing actuation of said valve if the temperature sensed is below a predetermined value.

19. The combination as defined in claim 15 and further comprising power operated conveyor means positioned to receive the material displaced through said discharge opening and convey the same to a location remote from said furnace, and means responsive to operation of said conveyor means for controlling the operation of said valve.

20. An apparatus of the type described for effecting discharge of solid material from a container therefor comprising two chambers communicating adjacent their bottoms with one of said chambers in communication with the bottom of the container for the material to be discharged and with the other of said chambers provided with a discharge opening adjacent its top, means providing a column of liquid externally of said chambers and communicating with the latter adjacent the bottoms thereof with the height of said column sufiicient to cause the liquid to enter said chambers and to stand therein at a height above the communication therebetween, and means for applying a pressure pulse to the surface of the liquid in said column thereby causing liquid to act as a piston for displacing a portion of said material through said discharge opening.

21. An apparatus as defined in claim wherein the connection of said column to said chambers is located adjacent the bottom of said one chamber on the side opposite the said communication between the chambers and substantially directed towards the other chamber whereby the liquid displaced from said column is directed for moving the material in said one chamber into said other chamber.

22. An apparatus as defined in claim 20 and further comprising means responsive to the presence of material in said container and operatively connected with the said means for applying a pressure pulse to selectively permit or prevent.

operation of the latter.

23. An apparatus as defined in claim 20 and further comprising timing means for repeatedly applying pressure pulses to the surface of the liquid in said column with periodic regularity, and means responsive to the height of material in said container and operatively connected to the said timing means for controlling the rate of application of said pressure pulses.

24. An apparatus of the type described for effecting discharge of solid material from a container therefor comprising two chambers comof the container for the material to be discharged to cause the liquid and with the other of said chambers provided with a discharge opening adjacent its top, means providing a column of liquid externally of said chambers and communicating with the latter adjacent the bottom thereof with the height of said column sufficient to cause the liquid to enter said chambers and to stand therein at a height above the communication therebetween, means for periodically applying pressure to the surface of the liquid in said column thereby causing the latter to act as a piston for displacing a portion of the material through the discharge opening, power operated conveyor means positioned to receive said material and convey the same to a location remote from said apparatus and means responsive to operation of said conveyor means for controlling the operation of said means for pcriodically applying pressure to the liquid in said column.

25. An apparatus of the effecting discharge of solid material from a container therefor, the said apparatus comprising two chambers communicating adjacent their bottoms with one of said chambers in communica tion with the bottom of the container for the material to be discharged and with the other of said chambers provided with a discharge opening adjacent its top, means providing a column of liquid externally of said chambers and communicating with the latter adjacent the bottoms thereof with the height of said column sufficient to enter said chambers and to stand therein at a height above the communication therebetween, means for applying fluid pressure to the surface of the liquid in said column at a rate sufficient to cause that liquid to act as a piston for displacing a portion of the material through said discharge opening, timing means operatively connected with said pressure applying means to control the duration of operation of the latter, and a second timing means operatively connected to control the intervals between operations of the first-mentioned timing means.

26. The combination as defined in claim 25 and further comprising means responsive to the height of the material in said furnace, a third timing means operative to provide intervals between operations of the first-mentioned timing means of different duration from those provided by the second mentioned timing means, and means operatively connecting the material height responsive means to the second and third mentioned timing means for selective operation thereof in accordance with the height of the material in the furnace.

27. In a shaft furnace, means providing a liquid seal at the bottom of said furnace including two chambers communicating adjacent their bottoms with the top of one of the chambers substantially aligned with the interior of said furnace and with the other of said chambers provided with a discharge opening adjacent its top, means for supplying liquid to said chambers to a height above the level of the communication therebetween, the dimensions of said chambers relative to that of the furnace being such that only a small quantity of liquid in said seal is exposed to material descending from said furnace in a given interval of time thereby preventing sudden generation of type described for excessive pressures, and means for periodically 23 applying a pulse of fluid pressure to the liquid in said seal at a rate suflicient to displace a portion oi'said liquid and the material from said Iurnace through the said discharge opening, whereby movement of the material through said furnace is effected by said periodically applied pressure pulses and any pressures generated by hot material contacting said liquid are relieved throughsaid seal.

HAROLD V. TRASK. KENNETH M. HALEY.

References Cited in the file of this patent UNITED STATES PATENTS Number Number Name Date Schutte Dee, 30, 1841 McGillin Feb. 17,' 1942 Voorhrees Feb. 9, 1943 Sherban June 13, 1950 Schilling Jan. 80, 1951 Engels et al Feb. 20, 1951 FOREIGN PATENTS Country Date Great Britain Aug. 26, 1949 

